A prominent Chinese lawyer and collector unveiled an old map on Monday that he and some supporters say should topple one of the central tenets of Western civilization: that Europeans were the first to sail around the world and discover America.

The Chinese map, which was drawn in 1763 but has a note on it saying it is a reproduction of a map dated 1418, presents the world as a globe with all the major continents rendered with an exactitude that European maps did not have for at least another century, after Columbus, Da Gama, Magellan, Dias and others had completed their renowned explorations.

But the map got a cool reception from some Chinese scholars and seems unlikely to persuade skeptics that Chinese seamen were the first to round the world.

Gong Yingyan, a historian at Zhejiang University and a leading map expert, argues that the map is too full of anachronisms to date from the 15th century. He said, for example, that Chinese cartographers did not use the style of projection seen in Mr. Liu's map - the rendering of a three-dimensional globe on a flat sheet - until after Europeans introduced that technique to the Chinese much later.